We measure the concentration of single-walled nanotubes (SWNTs) present in aqueous suspensions by a technique that involves surfactant removal followed by high-temperature oxidation and mass spectroscopy of the resulting products. We also analyze the shift in SWNT emission energy evident from photoluminescence excitation spectroscopy as the surfactant molecule is changed. Next we study spectroscopic changes as surfactant is gently removed by dialysis.
The effects of protonation on the structure of the carbon single-walled nanotube (SWNT) polymer composites were studied by solid-state nuclear magnetic resonance (NMR) techniques and Raman spectroscopy. In addition, solid-state <sup>13</sup>C NMR was used to elucidate the aggregation state of the SWNTs in the polymer films relative to pristine SWNTs.